A scroll compressor makes it possible to compress a gas. A compression stage of a scroll compressor comprises two interleaved scrolls in such a way as to suck and compress a gas. One of the scrolls is fixed while the other moves eccentrically without rotating.
A compression cycle comprises a step of sucking gas, then a step of compressing this gas and finally a step of discharging compressed gas. The eccentric movement of one of the scrolls in relation to the other allows for the suction of a gas from the external portion of the scrolls. The sucked gas forms a pocket of gas driven towards the center of the scrolls. As the pocket moves towards the center of the scrolls, it becomes smaller and smaller. As such, the pressure of the gas increases until the desired discharge pressure is reached. Once this pressure is reached, the gas is discharged, by unloading the pocket, via a discharge orifice at the center of the scrolls.
In industry, scroll compressors have different characteristics according to their application.
In the automotive cold industry, a scroll compressor comprises:
two scrolls made of aluminum, of which one of them does not have a coating and incorporates a scroll prop and the other incorporates a hard surface treatment,
top scroll seals that make it possible to guarantee the axial seal between the scrolls, and
a thrust ball bearing that provides both the taking of the axial forces that tend to separate the scrolls from one another and the anti-rotation of the orbiting scroll.
The disadvantage of the thrust ball bearing is based on its principle itself, which leads to having the axial forces transit only via contact points between the tracks and the balls, as such limiting the level of effort that is transmissible and the potential service life in relation to technologies that include a flat thrust bearing or a counter-pressure thrust bearing.
In addition, integrating a scroll prop can lead to a deterioration of the scroll whereon it is mounted due to a relative movement during operation between said prop and its scroll induced by the mounting clearances. This movement will be amplified as the deterioration of the bottom of the scroll occurs via matting and will generate a cutting of the scroll. This phenomenon therefore induces a lower service life with respect to technologies that do not include a scroll prop.
In the stationary cold industry, a scroll compressor comprises:
two scrolls made of cast iron,
top scroll seals for the axial seal between scrolls,
an Oldham seal made of aluminum carrying out the anti-rotation of the orbiting scroll, and
a flat thrust bearing made of cast iron that ensures the taking of the axial forces.
This type of compressor with a flat thrust bearing therefore makes it possible to overcome the weakness of the thrust ball bearing by replacing it with the flat thrust bearing. However, the use of the flat thrust bearing imposes a lubrication management that makes it possible to guarantee a film of oil between the orbiting scroll and the thrust bearing.
In another known solution of the stationary cold industry, a scroll compressor comprises:
two scrolls made of cast iron,
an Oldham seal made of aluminum that carries out the anti-rotation of the orbiting scroll, and
a counter-pressure thrust bearing made of cast iron that ensures both the taking of the axial forced and the axial seal between scrolls by using said counter-pressure in order to ensure the maintaining in contact thereof.
The operation of the counter-pressure thrust bearing is made possible through the use of the scroll made of cast iron. Indeed, cast iron is able to resist a strong level of friction and axial forces, contrary to aluminum.
This type of compressor with counter-pressure thrust bearing also makes it possible to overcome the weakness of the thrust ball bearing by replacing it with the counter-pressure thrust bearing. In addition, the counter-pressure effort makes it possible to overcome scroll seals and allows for very simplified lubrication management in this zone. However, the level of force of the counter pressure induces losses that are higher than those of the compressor with a flat thrust bearing.
These two compressors in the stationary cold industry are heavier and more cumbersome than that of the technology of the automotive cold industry due to the use of scrolls made of cast iron.
Document EP 2 312 163 discloses a scroll compressor comprising, contained in a sealed case, a section of an electric motor, a section of a compression mechanism connected to the section of the electric motor, an oil sump for the lubrication oil and providing the compression of a refrigerant fluid by the compression mechanism section. The refrigerant fluid used is a halogenated hydrocarbon or a hydrocarbon that each has a carbon-carbon double bond in their composition or a mixture containing one from the halogenated hydrocarbon and the hydrocarbon. A sliding surface of at least one of the two parties forming a sliding section wherein the two parts slide over one another in the sealed case is configured in such a way that an iron-base or aluminum-base metal is not exposed directly.
Document U.S. Pat. No. 6,079,962 discloses a scroll compressor wherein a component made of an aluminum alloy that has a surface intended to be in contact with another component of the scroll compressor comprises between 2 and 18% of graphite particles in said alloy in a region neighboring this surface.
These documents show the use of aluminum alloy in a scroll compressor but the solutions proposed here do not provide for having a scroll made of aluminum and a thrust bearing also made of aluminum. The coatings revealed in these documents are thin coatings of the OAC, OAD, phosphating, hard chromium, DLC, WCC, TiN, TiCN, etc. type. Such coatings are not suitable for operating with low lubrication.
This invention aims to suppress, or at least attenuate, all or a portion of the disadvantages of the aforementioned prior art.
In particular, this invention aims to propose a compression device that has high reliability while still remaining light.
As such this invention aims to allow for the use of aluminum in a compression device despite the high levels of pressure used in fields such as aeronautics.
In addition, this invention in particular has for purpose to overcome a complex lubrication management system without altering the reliability of the thrust bearing. A purpose of the invention is as such in particular to propose a solution that makes it possible to use light materials in a compression device operating with an elasto-hydrodynamic lubrication regime using a low quantity of lubricant.
Furthermore, this invention in particular aims to propose a compression device that has a long service life.
The compression device according to the invention will also more preferably be easy to adjust and/or not cumbersome and/or with a moderate cost price.